Nordic Nutrition Recommendations (NNR) recommend exclusive breastfeeding until 6 months, partial breastfeeding until 1 year or longer and irrespective of breastfeeding, avoiding solid foods before 4 months. Strong evidence was found for benefits of breastfeeding regarding growth and infections but limited/inconclusive evidence regarding atopic disease and asthma. Vitamin D is of special interest in the Nordic diet. The aim of this prospective study was to compare infant feeding and vitamin D between immunoglobulin E (IgE) sensitized (n = 14) and non-sensitized (n = 130) children at 6 years. Information on diet and vitamin D supplement use were collected with dietary recall (<5 months), 1-d food records (5 and 6 months) and 3-d weighed food records (12 months and 6 years). Serum-specific IgE-antibodies against milk, egg, cod, wheat, soy and peanut (cut-off specific IgE ≥ 0.35 kUA/L) were measured at 6 years and serum 25-hydroxyvitamin D at 12 months and 6 years. At 4 months, 57% of IgE sensitized vs. 23% of non-sensitized children (p < 0.01) had received solid food. At 12 months, IgE sensitized children had a lower intake of vitamin D (median (25th, 75th percentiles): 3.9 μg/d (3.2, 7.2) vs. 8.1 μg/d (4.4, 12.3), p = 0.03) and at 6 years, fewer used vitamin D supplements regularly (23% vs. 56%, p = 0.03). Introduction of solid foods prior to 4 months increased the odds of IgE-sensitization, OR = 4.9 (95%, CI = 1.4–16.6) and vitamin D supplement at 6 years decreased the odds of IgE-sensitization, OR = 0.2 (95%, CI = 0.1–0.98), adjusting for maternal smoking. These observations support the NNR in their recommendation against introducing complementary solid foods before the age of 4 months. Furthermore, they support encouraging vitamin D intake for young children at northern latitudes.

Background: Of the major peanut allergens, sensitivity to Ara h 2 has the highest prediction for clinical allergy. In this study, we evaluated sensitization to peanut components in Iceland and related Ara h 2-negative sensitization to clinical allergy. Methods: Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Bet v 1 IgEs were measured (ImmunoCAP) in 220 peanut IgE (Pn-IgE)-positive serum samples. Ara h 2 IgE-negative individuals were invited to an open peanut challenge and evaluated for Ara h 6 and 9 sensitization (ISAC microarray). Results: The Ara h 2 IgE-negative group (52.3%, 115/220) was older (p = 0.04) and more likely to have a history of pollen allergy than the Ara h 2-positive group (p < 0.001). Of the Ara h 2-negative participants, 24.3% were already consuming peanuts and 38.3% were unavailable. Of the 43 who underwent an open peanut challenge, 79% were negative, 14% were positive, and 7% were inconclusive. Those who reacted to peanuts had a higher Ara h 1 IgE than that of the tolerant participants, and 3 were positive to Ara h 6 IgE, and 2 of those subjects were monosensitized. Ara h 8 may have caused a positive reaction, while Ara h 9 did not. Conclusions: Half of the peanut-sensitized individuals in Iceland were not sensitized to the major allergen Ara h 2. Ara h 1, Ara h 3, and Ara h 6 sensitizations resulted in a positive open peanut challenge and they are therefore clinically important for individuals with a peanut allergy in Iceland.

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